A conventional magnetic recording medium has all the servo information buried in a magnetic data layer. The servo information cannot be overwritten during a writing process of recording data on the magnetic data layer.
Another conventional medium includes a magnetic data layer, and a physically separate magnetic layer as a dedicated servo layer for storing the servo information. However, a writing field from a recording/writing head may write the magnetic data layer only but not affect the dedicated servo layer, in other words, the servo information in the servo layer cannot be overwritten by the writing field from data recording head.